This relates generally to electronic devices, and more particularly, to electronic devices with displays.
Electronic devices often include displays. For example, cellular telephones and portable computers often include displays for presenting information to a user.
Liquid crystal displays contain a layer of liquid crystal material. Pixels in a liquid crystal display contain thin-film transistors and electrodes for applying electric fields to the liquid crystal material. A liquid crystal display includes substrate layers such as color filter layers and thin-film transistor layers. The liquid crystal layer of a liquid crystal layer is sandwiched between the substrate layers. Upper and lower polarizers are formed above and below the substrate layers. The strength of the electric field in each pixel controls the polarization state of the liquid crystal material associated with the pixel and thereby adjusts the brightness of the pixel.
The color filter layer in a liquid crystal display contains an array of color filter elements such as red, blue, and green elements and is used to provide the display with the ability to display color images. The thin-film transistor layer contains thin-film transistor circuitry that forms thin-film transistors and electrodes for the pixels.
A display may have a backlight unit that provides backlight illumination for the pixels. Backlight from the backlight unit travels outwardly through the layers of the display. White backlight that has been modulated in intensity using the liquid crystal layer, thin-film transistor circuitry, polarizers, and other display layers is converted to colored light as the white light passes through the color filter elements.
The color filter elements are typically formed within openings in a black matrix. The black matrix is a grid of opaque material that blocks stray light between adjacent pixels and hides underlying signal lines from view. The black matrix can help reduce color mixing between adjacent pixels and can reduce signal line visibility, but also absorbs a fraction of the backlight in the display, thereby reducing backlight efficiency. Low backlight efficiency can lead to excessive power consumption and reduced battery life in battery-powered devices.
It would therefore be desirable to be able to provide a display with improved backlight efficiency.